This invention relates to an improved adhesive tape tab for use on disposable diapers. More particularly, this invention relates to an improved adhesive tape tab which permits fastening forces on the tape to be distributed to both sides of a disposable diaper during use, and to certain embodiments of the diaper which are to be opened after a closure has been made without tearing the outside film of the diaper or the tape tab itself, and which can be repositioned and re-used for subsequent fastenings of the diaper.
It has become very common and practical to use adhesive tape tabs on disposable diapers. The practicality of tape tabs, rather than pins, is self-evident. One of the problems which has occurred, however, when using adhesive tape tabs is tearing of the outside film to which it is attached. When one part of the tape is secured to the plastic film and the other part is fastened to another part of the diaper during use, the stresses are often too great thereby causing the plastic film to tear. A technique to overcome this problem has been proposed in U.S. Pat. No. 3,848,594, whereby the stresses are transmitted to both the front and back surfaces of the diaper. However, there are limitations in the functional uses and versatility of the technique in the mentioned patent. As will be described hereinafter, versatility of the tape tab of the present invention offers specific advantages over the presently known tape tabs which distribute forces to both sides of the diaper.
There are also shortcomings in the use of adhesive tape tabs which become evident especially when the diaper needs checking for soiling or for repositioning. For instance, when a child reaches the stage of toilet training the diaper must be opened and removed, and if not soiled, could be used again. The prime or major shortcoming in the known adhesive tape tabs is the lack of easy separability from the diaper once the original closure has been made. To separate the adhesive tape tab from the surface of the diaper on most, if not all, occasions either the outside surface of the diaper, usually a thin, plastic film, is torn or the tape tab itself is torn. A torn tape tab or a torn diaper outside surface makes refastening very cumbersome if not, practically, impossible. Furthermore, the consumer has had to discard unsoiled diapers because the attempt to open the diaper has torn the outside of the diaper too much to make a subsequent closure. This lack of re-use is an economic disadvantage and an expensive burden due to the cost of disposable diapers.
The above tearing problems arise from use of a very thin plastic film as the outside surface on nearly all disposable diapers. This plastic film, being thin, is economical, flexible, somewhat supple, and most importantly, is impermeable so as to act as a fluid barrier for retaining fluids within the diaper. While the known adhesive tape tabs make a good, strong fastening on this film when the diaper is in use, the thin nature of the film allows the film to easily tear when fastening forces are too great or attempts are made to peel the tapes from the film. Of course, making the plastic films somewhat thicker is a possible means of increasing the strength of the film. However, the cost of the thicker film is increased, its flexibility and suppleness reduced, while no assurance is gained that tearing will not occur under variable tape fastening conditions.
Recently, there have been attempts to provide disposable diapers with adhesive tape tabs which can be used more than once. In U.S. Pat. No. 3,848,596, the tape tab fastening means provides an arrangement which is essentially useful for only two fastenings, the original and one more. Use of multiple release sheets on the tape tabs provides the refastening ability. The multiple release sheets are, however, limiting elements in the refastening or repositioning ability of the tapes, and add cost in the manufacture of the diapers. Besides the cost factor, the use of multiple release sheets does not overcome the problem of tearing either the outside of the diaper or the tape tab itself in order to open the diaper after the original closure has been made. In those instances when the outside diaper film is torn, the absorbent material inside the diaper is exposed, may drop out of the diaper in pieces and does not permit any neat and effective refastening of the diaper around the wearer. Consequently, the diaper has to be discard, even though it may not be soiled.
The tape fastener disclosed in U.S. Pat. No. 3,853,129 is so constructed as to be used on disposable diapers without the need of a release paper. The tape fastener has a middle segment having a plastic material with a retiform surface; the tape is folded when the diaper is in the non-operating position so that a releasable adhesive end surface of the tape lies against the surface of the plastic material. The middle plastic segment and the shape of the fold allows the tape tab to be used without a release paper. In use, however, this tape tab with the retiform plastic material creates additional holding power against the backing sheet of the diaper and cannot be separated after closure without, on most occasions, tearing the diaper backing sheet or tearing the tab itself.